310 BACTERIOLOGY. 



of a low degree of virulence, though they are, never- 

 theless, genuine diphtheria bacilli. 



For those organisms that are in all respects identical 

 with the virulent bacillus diphtherice, save for their in- 

 ability to kill guinea-pigs, the designation " pseudo- 

 diphtheritic bacillus " is usually employed, but from 

 such observations as those just cited we are inclined to 

 the opinion that pseudo-diphtheritic, as applied to an 

 organism in all respects identical with the genuine 

 bacillus, except that it is not fatal to susceptible ani- 

 mals, is a misnomer, and that it would be more nearly 

 correct to designate this organism as the attenuated or 

 non-virulent diphtheritic bacillus, reserving the term 

 "pseudo-diphtheritic" for that organism or group of 

 organisms (for there are probably several) that is enough 

 like the diptheria bacillus to attract attention, but is 

 distinguishable from it by certain morphological and 

 cultural peculiarities aside from the question of viru- 

 lence. 



It is a well-known fact that many pathogenic organ- 

 isms conspicuous among these being the micrococcus 

 lanceolatusj the staphylococcus pyogenes aureus, and 

 the group of so-called hemorrhagic septica3mia organ- 

 isms undergo marked variations in the degree of their 

 pathogenic properties, and yet these organisms, when 

 found either devoid of this peculiarity, or possessing it 

 to a diminished degree, are not designated as "pseudo" 

 forms, but simply as the organisms themselves, the viru- 

 lence of which, from various causes, has been modified. 



. Prepare cover-slip preparations from the 

 mouth-cavity of healthy individuals and from those 

 having decayed teeth. Do they correspond in any way 



